Method of threading studs



April 30, '1935; .1. M. I INDENMUTH l-:T AL

METHOD OF THREADING STUDS Filed July l2, 1935 Fg?. I. ga

l@ j? LQ 10 z Q /zz Pafenfea Apr. 3o, 193s METHOD OF THREADING STUDS Yloom; M. '..unaenmuth and James weir'ich, s Lebanon, Pa., assignors'j toBethlehem Steel Company, a corporation 'o f Pennsylvania Application.uly 12, 1933, SerialNo. 680,056 f UNITED"STMES PATENT' OFFICE v 12claims.

. invention Yrelates to an improved I.method of manufacturing heattreated studs and particularly to the method of threading the studs.

Heretofore, studsof this nature were made by heat treating long lengthsof bar stock andl threading the bar its full length except for thematerial at one end for gripping purposes, then cutting the threaded barto the desired studf.

lengths in a lathe. By this method the Jbar stock 'zis heat treatedinbundles which causes much Lwarping ofthe stock which must subsequentlybe straightened. It has been found .-diiicultgto straighten heat treatedbars so that vcorrect threads can be produced, and'it has also. beenIfound that lheatV treatingA in bundles and thestraightening operationoften produces extremely hard spots on the stock ,due to ununiformtreat-Y ment and to physical changes in the material resulting 'fromythe straightening operation. These hard spots cause excessive Wear onthe threading tools, also excessive heating to the extent `that 'thethreading operation must be interrupted at times to allow the dies tocool.,

This -frequently causes imperfection in .the Furthermore,

not pass inspection untilcorrected; Taking this method as av Whole, themanufacturing costs,

rejection losses and loss in material the bars are high. .i AInaccordance with our improved method of manufacturing studs, Wetake a hotrolled bar and at the ends of straighten it when cold if necessary. Thebar is manufacture of the" stud and comprises placingv a blank in a gripchuckand threading kit to the maximum length possible, after which` thethreaded end is placed in a speciallyprepared threaded grip on anothermachine that is perfectly aligned with its die-head and the chasersv areclosed over .the *threadedportion vand Ythe threading completed. Thisparticular die-head` is fitted with opposite hand chasers to that of thefirst machine Vbut with right hand threads and Y arranged torotateopposite to that of the first iwithout vvasteV of material'. 1

machine. YThe finishing of the thread is similar to backing a nutk oif astud, thus completing the thread whichy is continuousfrom end .to endand treatment'of long bars.

i holding members I3.

(c1. 1Z0-'1) l One of the objects is toprovide a method of manufacturingheat treated studs, whereby bete4` ter physical properties are obtainedin heat treatf, ing the short pieces than is possible lin batch Anotherobject is to eliminate'the straightening "of long heat treated bars andto eliminate rejections caused by bruised or imperfect threads.

The novel and principal object of this invention is to provide a methodfor threading the shortblanks so `as to form a 'continuous anduninterrupted thread from end to end ofthe blank without waste and toproduce, threads of uniform pitch and depth. W .n `The; novel featureslwill be more fully underf stood from the followingdescription and claimstaken with the` drawing, in which: `Figure lv is a horizontal sectionalView through the die-head and 'chuck of a threading machine andillustrates the first step in the threadingV L,

operation.

Fig. v2 is a horizontal sectional view through` I the die-head and chuckof another threading machine and illustrates the second or finishingstep inthe threading operation. 'Referring to Fig. l of thedrawing, I0indicates as-a'wholethe threading tool or die-head ofa Nationalthreading machine. `II indicatesthe chuck for` gripping and holding thework in' alignment -With thehead. i 2 are thethread Y' chasers mountedin the pivotally supported tool The members I3 areA f adaptedito beclosed by the action of the cone-1- faced clutch I4 When'pressedinto-engagement with the rearends of membersv I3. Members I 3 are'.arranged to vopen automatically when the clutch I4 iswithdrawn so as torelease the chasers from the'stud I5 to allow its removal from thedieehead. I 6 are adjusting screws for the chasers. I1 indicatesa fixedgrip and I'indicates a movable grip for fchu'cking the work. 'I9` is thescrew for actuating grip` I 8.` r2l) is theflever for .rotating thescrew to open orclose the chuck. Since allk of these parts and theirfunctionsare common to various types of machines,V further descriptionis believed unnecessary for an understanding to thosev skilled in theart. i:

Fig. 2Y illustrates the die-head of another threading machine, which isYsimilar in mechani-v cal features to the die-head as shown inFig.V l'.TheV only. difference betweenY thevtwo headsv resides in the chasers 2 IVbeing mounted in reversedv relation to the .chasers I2 of Fig. 1. Bothvsets of chaserscare provided with right hand threads of equalcharacteristics.. 'Ihe'chuck 22of this ma` chine is tted with threadedgrips 23 and 24 so as to engage the threaded end of the partly finishedstud. The other features of the chuck being similar to those of Fig. l.

In operation, one end of a blank stud is mounted in the grips l1 and i8which align the blank with the axis of the die-head IB. The chuck Il isthen advanced toward the .closed rotating chasers l2 which thread' thestud vover a major portion of its length. After the stud is threaded tothe maximum length the die-head is arranged so as to automatically openand the partly threaded stud is withdrawn from the head and' removedfrom the chuck. Thus far the .threading is similar to an ordinarymethodof threading 'one end of a bolt or the like. The nektand .novelstepV comprises reversing the stud and placing its threaded end in thethreaded grips of chuck- 22 and entering the unthreaded end of the studyinto the opened chasers 2l, after which the chasers are closed upon thethreads as shown in Fig. 2 so as to register therewith. The die-head `ofthis to that of the -rstmachine andthe stud is drawn outwardly throughthe chasers-'to complete the threading of the stud. It will be notedthat the movement of thechuck in Fig. '2 is opposite to that in Fig. 1during the threading operation as indicated by the arrows. By threading`a stud after this manner we obtain a continuous and uninterruptedthread of uniformA depthV and pitch from end to endV and without anywaste as in theV caseV where a long rod is ordinarily threaded as far asthe chuck will permit and then having to `discardthe chuckedorunthreaded end portion.

It is obvious that by this method of threading there is no overlappingof threads such as proy duced when a stud is threaded from both ends onthe same machine, due to the fact that lthe Yiinishing of the Athreadstarts where the un- Vwill be automatically ejected or pushedout of thedie-head without the assisting action of the lead screw which normallycauses the chuck to move awayV from the die-head. It will thus be seen.that the pitch or lead of the thread is not" entirely dependent upon'the lead screw to pull lthe work through the chasers'because thepreviously threaded portionv of the fstud establishes Sa fixed lead forthe unthreaded portion. However, it isbelieved advisable to use the leadscrew for moving the chuck as it tends to reduce wear n the chasers.

Having thus Vdevised :'a methodrpfor Athreading., studs from end toendrwith a continuous thread.

l we are enabled to eliminate the din'iculties encountered in having :tostraighten lon'g vrods after theyhave been'heat treated, because bythismethod we straighten the rod', if necessary, before 1 it is heat treatedand then treat the short pieces which require'no straightening.

In addition to the savings of this new method over the present common.method amore accuous .threading of long bars. and with resulting longerlife to the chasers. The mari'ing ofthe l threads in gripping is alsoYeliminated by this new method, which previously caused vconsiderableobvious that the work may be rotated in a nonslidabl chuck` and thechasers mounted in a slidable toolholder. In other words, it matters"not which `is vtherotatable or slidable member,

and itQ-vi'fillV be understood that in its `broader aspects, theinvention' is not limited to the specific 4means shown vcovering thevarious movements and actions described, producing the resultsHavirigdeseribed durf-invention, what we @iai-m as new `and desire tosecure by LettersPatent,-i"s: machine is then rotated in a directionopposite Y l. A method of completely threading a partly threaded'studo'r the like, comprising gripping `the injurethe threads and insertingthe uintlireaded end into anopened die-head of a threading fha-- chine,closingthe dies of said-head upon a' por'- partlylthre'adirig the stu'dfrom one end, then gripping' the threaded end ofthe stud and-insertingthe unthreadedend into an opened die-head of a threading machine',registering 'the dies f said-head with the previously formed threads,-rotating said head kand withdrawing the stud from the head. so as tocomplete the thread.

3. A method of completely threading a partly threaded stud vor the like,comprising' 'gripping the threaded endof the stud in a chuck, insertingthe 'Unthreaded end into an opened ydie- `headrof a'thread'ing machine,closing the dies` of said head'upon a Vthreaded'portion of thev stud soas .toV establish a lead for threading the unnn'ished portion, androtating said head t'o in'ov'e the stud automatically through-theheadbythe action of said lead,` whereby to produce a continul ity of thethread from end to end'.

4. .A- method of cutting c'on'tinuous screw threads on a stud,comprising first partly threading the-stud fromv one endin a; threadingma-1 chine having a'rotatable die-headby feeding the stud into the dies,thenV removing the stud from this machine andiinish threading the sameby inserting the."unthreaded endfofth'e stud into'V the rotatabledie-head of another threading ma'- chine and drawing the stud completethe thread. f

5.V A method [of cutting continuous lscrew threads, .comprising :feedingthe piece to be threaded into a rotating threadingV tool 't partlythreadthe piece, transferring the partly threaded piece toanotherthr'eading tool and inserting the unthreaded portion of thepieceinto said tool, registering'isaid second tool with the previouslyformedv threads, rotating vsaid tool and simultaneously withdrawing thepiece so as to com;

pletely thread the s'ame throughout its` entire` length.

`6., A :method of .'cuttingi 'continuous screw.

threads, comprising feeding `the Vpiece to be '60 through thdies tothreaded into a rotating threading tool to partly thread the piece,transferring the partly threaded piece to another threading tool ttedwith a cutter of opposite hand to the first machine, reversing the pieceand registering said cutter with the previously formed threads, rotatingsaid tool in a direction opposite to that of the first machine andsimultaneously causing relative movement between said tool and theunthreaded end of the piece so as to uniformly thread the piece from endto end in a continuous manner.

7. A method of cutting continuous screw threads on a stud, comprisingmounting a blank stud in a chuck of a threading machine, feeding thestud into a rotating die-head providedV with chasers to thread the studover a portion of its length, removing the partly threaded stud from themachine and mounting 'its threaded end in a chuck of a similar machine,Vregistering the chasers of this machine with a threaded portion or" thestud, and finish threading the stud so as to form a continuous thread ofuniform depth and pitch from end to end.

8. A method of cutting `continuous screw threads on a stud, comprisingmounting a blank stud in a chuck of a threading machine, feeding thestud into a rotating die-head provided with chasers to partly thread thestud, removing the partly threaded stud from the machine,v reversing thestud and mounting its threaded end in a chuck of another similarthreading machine, inserting the stud into thedie-head and registeringthe chasers of this machine with va threaded portion of the stud,rotating the die-head in a counter direction to that of the firstmachine, and feeding the stud away from the die-head to complete thethreading operation.

9. A method of cutting continuous threads on a stud, comprising mountingthe stud in a chuck member of a threading machine, mounting threadchasers in a tool holding member of said machine, rotating one of saidmembers and simultaneously feeding the other member toward the rotatingmember to thread one end of the stud, transferring the stud to anotherthreading machine having a tool holding member tted with thread chasersofr opposite hand to those of the `first machine, mounting the threadedend of the stud in the chuck member of the machine, closing the chaserson the previously cut threads of the stud, rotating one of said membersin a direction opposite to that of the first machine and simultaneouslywithdrawing thev other member to completely thread the stud in a formmanner.

1D. A method of cutting continuous right-hand threads the full length ofa stud without Waste,

continuous and uni-V comprising threading in one machine the greaterportion of the stud after the common manner of threading a bolt, thenreversing the stud and gripping its threaded end in a threaded grip ofanother threading machine which is specially fitted with oppositevhandchasers but with righthand threadsplacing the partly threaded studbetweenthe chasers and closing the chasers over the threaded portion ofthe stud, rotating the chasers in a direction opposite to that of therst machine and simultaneously drawing the unthreaded end lof the studthrough the chasers so as to cut threads on the unfinished end of thestud in a continuous manner and of uniform depth. I ,s

l1. A method of cutting continuous screw threads the full length of astud Without waste, comprising gripping a blank stud in a chuck of athreading machine having an opening and closing die-head and providedwith chasers, closing the die-head androtating same in a clockwisedirection, feeding the studinto the chasers to thread thestud over aportion of its length, removing the partly threaded stud fromthermachine, reversing the stud and gripping its threaded end in athreaded chuck of another threading machine having a die-head similar tothe first machine but fitted with reverse hand chasers, opening thedie-head and inserting the unthreaded end into same to the extent thatthe blank end of the stud will. be to the rear of the chasers, closingthe chasers on a threaded portion of the stud, rotating the die-headcounter-clockwise, and simultaneouslymoving the stud through thedie-head so as to continue the cutting of the threads formed by theiirst machine in an uninterrupted manner.

12. A method of cutting continuous screw threads the full length of astud without waste, comprising gripping a rblank stud in a chuck of athreading machine having an opening and closing die-head and providedwith chasers, feeding the stud into a'closed die-head and simultaneouslyrotating same in a clockwise direction vto thread the stud over aportionA of its length, removing the partly threaded stud from themachine, reversing the stud and gripping its threaded end in a threadedchuck of another threading machine

